1. Field of Invention
The present invention pertains to the field of software systems. More particularly, this invention relates to self-describing attribute vocabularies in a software system.
2. Art Background
Computer systems and networks of computer systems and similar devices may be viewed as a collection of resources. These resources may include software resources such as files, data bases, application programs, and information services. These resources may also include hardware resources such as storage devices, printers, communication devices, and display devices to name only a few examples. These resources may be local resources of a computer system or similar device or may be remote resources accessible via a network connection to one or more other computer systems or similar devices.
Software systems for computer systems and similar devices commonly include service providers which are adapted to particular types of resources. One example of a service provider is a file server. Other examples of service providers include printer servers, digital document servers, as well as providers of information services such as news, stock quotes, etc. A software program that accesses a resource of a service provider may be referred to as a client of the service provider.
Software systems for computer systems and similar devices commonly implement protocols that enable potential clients to discover resources and that enable service providers to advertise their resources to potential clients. In such a system, a service provider usually formulates attributes that describe its capabilities and a potential client usually formulates attributes that describe requirements about a desired resource. Such a system typically enables the potential client to discover a desired resource by determining whether a match occurs between the attributes that describe the desired resource and the attributes that describe the capabilities of the service providers.
Unfortunately, prior protocols for resource discovery typically limit the ability of service providers to advertise their resources. For example, a printer service provider may not be able to advertise incentives associated with its printer resources in a system in which attributes are limited to hardware related factors such as resolution, fonts, and colors, etc. In addition, such prior systems may make it difficult to add new types of resources to a software system. For example, attributes which are adapted to files or hardware devices may not be suitable for new types of resources such as news or stock quotes or other information services.
A software system is disclosed with self-describing attribute vocabularies that enhance the capability of service providers to advertise their resources and that facilitate the addition of new types of resources and attributes to the system. The self-describing attribute vocabularies are active entities that are made available as resources in the software system. The software system enables vocabulary service providers to easily make new attribute vocabularies available to tasks executing in the software system and enables tasks to discover resources in terms of one or more of the self-describing attribute vocabularies.
Each self-describing attribute vocabulary is characterized by a corresponding set of attribute properties and a corresponding set of matching rules that are adapted to the corresponding attribute properties. The software system includes a matching engine that enables a service provider of a resource to describe the resource to the software system in terms of any one or more of the self-describing attribute vocabularies. The attribute vocabularies are self-describing in that the attribute properties and associated matching rules can vary widely among the attribute vocabularies. The matching engine implements mechanisms that enable software tasks to discover and use any one or more of the self-describing attribute vocabularies and the matching engine adapts its attribute-based lookup operations for resources to the appropriate set of matching rules.
Other features and advantages of the present invention will be apparent from the detailed description that follows.